We developed an isolated perfused rat liver preparation (IPL) suitable for pharmacokinetic studies with xenobiotics. This IPL was used to study uptake, metabolism, accumulation, and excretion of PCBs. We used an homologous series of PCBs (4-chlorobiphenyl, I; 4,4'- dichlorobiphenyl, II; 2,4,5,2',5'-pentachlorobiphenyl, III; and 2,4,5,2',4',5'-hexachlorobiphenyl, IV) to investigate the relationship of degree of chlorination of PCBs to their uptake, metabolism, and excretion by the liver preparations. These studies were directed towards determining the role of the liver in the overall whole animal disposition of PCBs.